<!DOCTYPE html>
<html lang="en" xmlns:v-on="http://www.w3.org/1999/xhtml">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<div id="app">
  <button v-on:click="sayHi">
    click me
  </button>
</div>
<!--导入vue.js-->
<script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>

<script>
  var vm = new Vue({
    el: "#app",
    data: {
      message: "fmj"
    },
    methods:{  //方法必须定义在Vue的Method对象中  v-on:事件
        sayHi: function (){
          alert(this.message);
        }
    }
  });
</script>
</body>
</html>